Assessing the proposed association between tooth agenesis and taurodontism in 975 paediatric subjects

Association between craniofacial patterns and third molar agenesis in orthodontic patients

PURPOSE

Third molar agenesis (TMA) is the most common craniofacial anomaly and has been associated with craniofacial patterns in different populations. Therefore, the aim of this retrospective cross-sectional study was to assess a possible association between craniofacial patterns and TMA in German orthodontic patients.

METHODS

Patients undergoing orthodontic treatment with dental records including anamnesis, pretreatment lateral cephalograms and orthopantomograms were evaluated. Cephalometric analyses were conducted digitally and lines, angles and proportions were measured to investigate craniofacial morphology. Skeletal classes were determined by the individualised Wits appraisal and ANB angle. The TMA was identified with the help of orthopantomograms. Patients showing agenesis of at least one third molar were included in the TMA group. Statistical analysis was performed to assess the association between TMA and craniofacial patterns (α of p ≤ 0.05).

RESULTS

A total of 148 patients were included, 40 (27.0%) presented at least one missing tooth (TMA group) and 108 (73.0%) showed full dentition (control group). Skeletal class determined by the individualised Wits appraisal revealed statistical significance between the TMA and control groups (p = 0.022), in which TMA patients were 11 times more likely to present with an individualised skeletal class III (odds ratio 11.3, 95% confidence interval 1.7-139.5). Skeletal cephalometric analysis revealed no statistical differences between TMA and control groups for any further angular, linear and proportional parameters.

CONCLUSION

Third molar agenesis was associated with skeletal class III determined by the individualised Wits appraisal.

Potential Association of Molar-Incisor Hypomineralization (MIH) with Dental Agenesis and Infraoccluded Deciduous Molars: Is MIH Related to Dental Anomaly Pattern (DAP)? An Observational Cross-Sectional Study

Background: Dental Anomaly Pattern (DAP) is a collection of morphologic, numeric, and eruptive anomalies of teeth that are often observed together, suggesting a potential genetic relationship. Our objective was to assess the potential associations of Molar-Incisor Hypomineralization (MIH), a common developmental defect of enamel mineralization with a controversial etiology, with two specific components of DAP: (1) agenesis (AG) and (2) infraoccluded deciduous molars (IODM). Establishing such an association between MIH and one or both anomalies would provide evidence supporting a genetic link between MIH and DAP. Methods: We examined pretreatment intraoral standardized photographies and panoramic radiographs from 574 children aged 8-14 years, 287 having MIH and 287 without MIH, comparing the frequencies of AG and IODM in both groups. The subject samples were sourced from the databases of the orthodontic department at a university hospital. Results: The frequencies of AG in the MIH and non-MIH groups were 7% and 8%, respectively (p = 0.751). The corresponding frequencies of IODM were 27% and 19.2%, respectively (p = 0.082). That is, children with MIH did not exhibit an increased frequency of AG or IODM compared to those without MIH. Conclusions: These findings do not support the inclusion of MIH in DAP. Nevertheless, further analysis of possible associations is necessary to definitively validate or invalidate this hypothesis.

Personalized and Complex Esthetic Oral Rehabilitation in a Case of Non-Syndromic Oligodontia

Dental agenesis is one of the most common developmental anomalies in humans and it is frequently associated with several other oral abnormalities. The present case describes non-familial agenesis of permanent teeth in a twenty-one-year-old boy with no apparent systemic abnormalities. The treatment included a personalized and interdisciplinary approach involving endodontics, orthodontics, implant-supported restorations and prosthetic treatments. The treatment plan was thoroughly elaborated using photographic analysis, study models, orthopantomogram, CBCT and cephalograms. Virtual smile design, diagnostic waxing and mock-ups previsualized the treatment objectives. The edentulous spaces were reconstructed by inserting dental implants and monolithic zirconia implant-supported restorations. The final results showed a highly esthetic and functional rehabilitation. Periodic check-ups have shown that the stability of the result is well maintained and that the implant-supported restorations are an optimal solution for patients with multiple anodontia.

A 32-month evaluation of lithium disilicate cantilever resin-bonded fixed dental prostheses to replace a missing maxillary incisor

STATEMENT OF PROBLEM

The absence of a tooth in the esthetic zone can cause emotional and social distress. The use of minimally invasive and visually pleasing lithium disilicate resin-bonded fixed dental prostheses (RBFDPs) may be a suitable option for replacing a missing maxillary incisor. However, the available literature on lithium disilicate cantilever RBFDPs is limited.

PURPOSE

This retrospective multicenter study assessed the survival and success rates of lithium disilicate anterior cantilever RBFDPs with an average follow-up period of 3 years up to 9 years.

MATERIAL AND METHODS

RBFDPs delivered by 3 operators were clinically assessed for survival using a modified United States Public Health Service criteria list. The incidence density was determined for each criterion and operator. The standard error and 95% confidence interval were calculated for each incidence density difference (α=.05 for all analyses).

RESULTS

A total of 108 RBFDPs were evaluated after a mean period of 32.45 months, ranging from 14 days to 111 months. None of the restorations exhibited failure, carious lesions, or fractures during the follow-up period. The primary reasons for reduced success rates were inflammation of the surrounding soft tissues and discoloration, with incidence densities of 0.074 and 0.057 per year, respectively. Significant differences were observed among RBFDPs from different operators for criteria that included adaptation, color match, marginal adaptation, polishability, surface staining, gingival health, and antagonist wear.

CONCLUSIONS

Cantilever lithium disilicate RBFDPs appear to be suitable for short-term restoration. RBFDPs exhibited visible changes after short-term follow-up. However, these changes did not result in failure.

Exploring the Association Between Genetic Polymorphisms in Genes Involved in Craniofacial Development and Isolated Tooth Agenesis

Tooth agenesis is a common congenital anomaly in humans and is more common in oral cleft patients than in the general population. Many previous studies suggested that oral cleft and tooth agenesis share a similar genetic background. Therefore, this study explored the association between isolated tooth agenesis and genetic polymorphisms in genes that are crucial for craniofacial and tooth development. Panoramic radiographs, anamnesis, and genomic DNA from 273 patients were included. Patients were classified as tooth agenesis present, when at least one permanent tooth was congenitally missing. Patients with syndromes and oral cleft were excluded. Only unrelated patients were included. The genetic polymorphisms in BMP2 (rs235768 and rs1005464), BMP4 (rs17563), RUNX2 (rs59983488 and rs1200425), and SMAD6 (rs3934908 and rs2119261) were genotyped by real-time polymerase chain reaction. Genotype and allele distributions were compared between the tooth agenesis phenotypes and controls by Chi-square test. Haplotype and diplotype analysis were also performed, in addition to multivariate analysis (alpha of 0.05). A total of 86 tooth agenesis cases and 187 controls were evaluated. For the rs235768 in BMP2, patients carrying TT genotype have higher chance to present tooth agenesis [p < 0.001; prevalence ratio (PR) = 8.29; 95% confidence interval (CI) = 4.26–16.10]. The TT genotype in rs3934908 (SMAD6) was associated with higher chance to present third molar agenesis (p = 0.023; PR = 3.25; 95% CI = 1.17–8.99). BMP2 was also associated in haplotype and diplotype analysis with tooth agenesis. In conclusion, genetic polymorphisms in BMP2 and SMAD6 were associated with isolated tooth agenesis.

Multiple root canals in the maxillary molar: an unusual case report

Background

The objective of this report was to highlight the importance of using a dental operating microscope (DOM) to locate supernumerary canals and diagnose variations in root canals using cone-beam computed tomographic (CBCT) images.

Case presentation

A 35-year-old Chinese female had repeated swelling in the upper right posterior maxilla for 3 months and was referred to evaluate symptomatic apical periodontitis and mesotaurodonts for upper right first permanent molar and upper right second permanent molar. Root canal therapy was proposed and conducted with the use of DOM and CBCT.

Conclusions

Proper diagnosis and careful clinicoradiological examination are necessary, and it is essential to reinforce the knowledge of the rare morphology of root canals for clinicians.

Taurodontism in the first permanent molars in Van der Woude syndrome compared to isolated cleft palate

OBJECTIVES

To analyse prevalence, pattern, and severity of taurodontism in individuals with Van der Woude syndrome (VWS) exhibiting cleft palate and compare with aged-matched non-syndromic cleft palate (NSCP) and non-cleft controls.

MATERIALS AND METHODS

One hundred and seventy-eight dental panoramic tomographs (DPTs) (105 girls and 73 boys) consisting of 42 VWS patients (x¯=8.55±1.02 years), 42 NSCP patients (x¯=8.59±1.02 years), and 94 normative non-cleft children (x¯=8.79±1.16 years) were assessed and their first permanent molars evaluated. Measurement 3 of the taurodontism index developed by Shifman and Chanannel with the Tulensalo modification was used. Prevalence, pattern, and severity were compared between groups. Statistical differences were determined by one-way analysis of variance and Fisher test. Repeatability was calculated by Cohens Kappa test.

RESULTS

The prevalence of taurodontic molars was 59.5% in VWS, 45.2% in NSCP, and 26.6% in non-cleft controls. The prevalence and severity of taurodontism in VWS and NSCP were significantly higher than in non-cleft children in all first permanent molars. There was no significant difference in prevalence and severity between VWS and NSCP. The odds for having taurodontism in the VWS group was approximately double compared to the NSCP group. Most of the taurodontic molars showed hypotaurodontism and taurodontism occurred bilaterally more frequently than unilaterally.

CONCLUSION

This study shows a higher prevalence of taurodontism in VWS and NSCP. Most taurodontic molars are hypotaurodontic and most occur bilaterally.

The global distribution of permanent canine hypodontia: A systematic review

Objective

To systematically review studies on canine agenesis prevalence in different populations and continents, based on the jaw, sex, location, and associated dental anomalies.

Methods

Electronic and hand searches of English literature in PubMed, Web of Science, Scopus, OpenGrey, and Science Direct were conducted, and the authors were contacted when necessary. Observational studies (population-based, hospital/clinic-based, and cross-sectional) were included. For study appraisal and synthesis, duplicate selection was performed independently by two reviewers. Study quality was assessed using a modified Strengthening the Reporting of Observational Studies in Epidemiology checklist, with main outcome of prevalence of canine agenesis.

Results

The global population prevalence of canine agenesis was 0.30% (0.0-4.7%), highest in Asia (0.54%), followed by Africa (0.33%), and the least in Europe and South America (0.19% in both continents). Canine agenesis was more common in the maxilla (88.57%), followed by both maxilla and mandible (8.57%), and the least common was mandible-only presentation (2.86%). The condition was more common in females (female:male ratio = 1.23), except in Asia (female:male ratio = 0.88) and Africa (female:male ratio = 1). In Asia, unilateral agenesis was almost twice as prevalent as bilateral, but in Europe, the bilateral form was more common.

Conclusions

The overall prevalence of canine agenesis is 0.30%, with the highest prevalence in Asia, followed by Africa, Europe, and South America. The condition is more common in the maxilla than the mandible, and in females than males (except in Asia and Africa), with unilateral agenesis being more common in Asia and the bilateral form showing a greater prevalence in Europe.

Dental and craniofacial alterations in long-term survivors of childhood head and neck rhabdomyosarcoma

OBJECTIVE

Rhabdomyosarcoma (RMS) represents the most common soft tissue sarcoma that affects children. Treatment involves chemoradiotherapy. This study aimed at evaluating the long-term alterations to teeth and cranial bones in children, teenagers, and young adults after oncologic treatment.

STUDY DESIGN

We conducted a cross-sectional study of patients undergoing treatment for head and neck RMS between 1988 and 2011. We evaluated demographic, clinical, and treatment data and performed panoramic radiography, cephalometry, and photography.

RESULTS

We evaluated 27 long-term survivors, most of whom had been treated between ages 0 to 5 years (51.9%). The total radiation dose applied was 50.4 Gy, and the chemotherapy combination included vincristine, actinomycin D, and cyclophosphamide in 51.9% of the cases. We observed 603 dental alterations, among which 377 (62.7%) occurred in patients ages 0 to 5 years, and root shortening was the most frequent alteration observed (24.2%). With regard to facial bones, 74% of the patients had some level of facial asymmetry, 70.4% had reduced facial depth, 48.4% had mandibles of short size, and 77.8% had reduced facial height.

CONCLUSIONS

Children submitted to RMS treatment involving chemotherapy and radiotherapy displayed significant dental and craniofacial alterations, especially when treatment occurred between ages 0 and 5 years.

Prevalence of Taurodont Molars in a Selected Iranian Adult Population

Introduction:

Taurodontism is an anomaly characterized by elongated crowns and consumedly apical location of the bifurcation area. This study aimed to determine the prevalence of taurodontism in molars based on digital panoramic radiographies in eight cities of Iran.

Methods and Materials:

This descriptive cross-sectional study was conducted on 2360 digital panoramic radiographs taken for different treatment purposes. Demographic information of patients was recorded and radiographs were evaluated for presence of taurodont molars. The prevalence rates were calculated and the data were analyzed using SPSS software version 18 via paired t-test, chi square test and ANOVA.

Results:

A total of 2360 panoramic radiographs (from 51.4% male and 48.6% female patients) were evaluated and the prevalence of taurodontism was reported 22.9% (22.6% in males and 23.3% in females) (P>0.05). Its prevalence was 51.67% in the right and 48.33% in the left quadrants (P>0.05), 34.1% in the mandible and 65.9% in the maxilla (P=0.000) and 79.52% in the second and 20.48% in the first molar (P=0.000). The prevalence of hypotaurodontism, mesotaurodontism and hypertaurodontism was 84.13%, 11.07% and 4.8%, respectively.

Conclusion:

The prevalence of taurodont molars was high in Iran and it was more common in the second molars and in the maxilla. Hypotaurodontism had the highest prevalence.

Association between Tooth Agenesis and Skeletal Malocclusions

Objectives

The aim of this study was to evaluate the association between tooth agenesis and skeletal malocclusions in Brazilian non-syndromic orthodontic patients.

Material and Methods

Pretreatment orthodontic records of 348 patients of both genders and with various skeletal malocclusions were examined. Tooth agenesis was evaluated in panoramic radiographs. Angular measurements were taken from lateral cephalometric radiographs to classify the patient’s malocclusion as skeletal Class I, Class II and Class III. Subjects were divided into 2 groups, “with tooth agenesis” and “without tooth agenesis”. Chi-square or Fisher exact test was used to compare categorical data. ANOVA with Tukey’s post-test was used for means comparisons. An alpha of 5% was established.

Results

From 348 analysed patients, 28 presented tooth agenesis. There was no difference between genders (P = 0.27) nor mean age (P = 0.16). The most prevalent skeletal malocclusion was Class I (63.11%), followed by Class II (25.94%), and Class III (10.95%). The mean of congenitally missing teeth was 1.3 (SD 0.13). Thirteen subjects had premolar agenesis, 13 upper lateral incisor agenesis, 4 lower incisor agenesis and 2 molars agenesis. The group with tooth agenesis presented A point-nasion-B point (ANB) angle smaller (1.66 [SD 2.52]) than the group without tooth agenesis (2.86 [SD 2.49]) (P = 0.01). ANB angle had a negative correlation with the number of congenitally missing teeth (P = 0.039; r = -0.39).

Conclusions

Tooth agenesis is associated with a smaller A point-nasion-B point angle and is negatively correlated with the number of congenitally missing teeth.

Taurodontism, Root Dilaceration, and Tooth Transposition: A Radiographic Study of a Population With Nonsyndromic Cleft Lip and/or Palate

OBJECTIVES

In an effort to contribute to proper dental planning and define possible dental phenotypes of nonsyndromic cleft lip and/or palate (CL/P), this study aimed to investigate the occurrence of taurodontism, root dilaceration, and tooth transposition in persons with nonsyndromic CL/P, specifically analyzing the differences among gender, cleft types, and the most affected teeth.

DESIGN

This retrospective study analyzed 974 panoramic x-rays from nonsyndromic Brazilians older than 16 years and categorized into the following four groups: group 1, 250 persons with unilateral cleft lip and palate; group 2, 250 persons with unilateral cleft lip; group 3, 224 persons with cleft palate; and a control group of 250 persons without clefts. Radiographs were digitalized with a scanner and analyzed.

RESULTS

In the Brazilian population studied, the prevalence of taurodontism was 60.4% in group 1, 62.4% in group 2, 67.0% in group 3, and 42.8% in the control group. Root dilacerations had a prevalence of 31.2% in group 1, 29.6% in group 2, 26.3% in group 3, and 27.2% in the control group. The teeth most affected by taurodontism were 17 and 27; whereas root dilacerations were most common in teeth 38 and 48. No tooth transpositions were found in any radiograph analyzed.

CONCLUSIONS

Taurodontism is significantly more prevalent in Brazilians with nonsyndromic CL/P than in persons without clefts; whereas the prevalence of root dilaceration no different from that in the control group. However, root dilacerations in anterior teeth were increased in groups 1 and 2 when compared to the control group.

Assessing the association of taurodontism with numeric dentition anomalies in an adult central Indian population

AIM

To study the association between taurodontism and numeric anomalies in adult population.

MATERIALS AND METHODS

Out of 1,012; 946 panoramic radiographs and dental records were retrospectively assessed to determine the presence of dental agenesis and supernumerary and taurodont teeth.

RESULTS

Taurodontism of one or more teeth was observed in 164 cases (97 females and 67 males). Hypodontia was observed in 148 patients (84 females and 64 males) with 62 patients having associated taurodontism (38 females, 24 males), oligodontia in 12 patients (five females and seven males) of whom nine patients also had taurodontism of one or more teeth (five females and four males). Forty-five patients (32 females and 13 males) presented with 57 supernumerary teeth (ST) with 12 patients having simultaneous presence of taurodontic tooth (seven females and five males).

CONCLUSION

Our study suggests a preferential association between tooth agenesis and taurodontism; however, such association was not observed in individuals with hyperdontia. Understanding the nature of this preferential association may be of importance in determining the etiology of both conditions. This association may also define a subphenotype for future genetic studies on dental development. Further molecular studies are necessary to verify the etiology and mechanism of taurodontism associated with tooth agenesis.

Genetic basis of dental agenesis--molecular genetics patterning clinical dentistry

Tooth agenesis is one of the most common congenital malformations in humans. Hypodontia can either occur as an isolated condition (non-syndromic hypodontia) or can be associated with a syndrome (syndromic hypodontia), highlighting the heterogeneity of the condition. Though much progress has been made to identify the developmental basis of tooth formation, knowledge of the etiological basis of inherited tooth loss is still lacking. To date, the mutation spectra of non-syndromic form of familial and sporadic tooth agenesis in humans have revealed defects in various such genes that encode transcription factors, MSX1 and PAX9 or genes that code for a protein involved in canonical Wnt signaling (AXIN2), and a transmembrane receptor of fibroblast growth factors (FGFR1). The aim of this paper is to review the current literature on the molecular mechanisms responsible for selective hypodontia in humans and to present a detailed overview of causative genes and syndromes associated with hypodontia.

Prevalence of Dental Anomalies in Patients with Nonsyndromic Cleft Lip and/or Palate in a Brazilian Population

Objective

Many studies have demonstrated a high frequency of dental anomalies in patients with cleft lip and/or palate. Because dental anomalies may complicate dental treatment, we investigated the prevalence of dental anomalies in a group of Brazilian patients with nonsyndromic cleft lip and/or palate.

Design, Participants, Setting

Retrospective analysis was performed using clinical records of 296 patients aged between 12 and 30 years with repaired nonsyndromic cleft lip and/or palate without history of tooth extraction and orthodontic treatment. Associations between oral clefts and presence of dental anomalies outside the cleft area were investigated.

Results

Dental anomalies were identified in 39.9% of the nonsyndromic cleft lip and/or palate patients, and tooth agenesis (47.5%), impacted tooth (13.1%), and microdontia (12.7%) were the most common anomalies. Cleft lip patients were less affected by dental anomalies compared with cleft palate or cleft lip and palate patients ( p = .057). Specifically, patients with unilateral cleft lip and palate were significantly more affected by dental anomalies than those with bilateral cleft lip and palate ( p = .00002), and individuals with unilateral complete cleft lip and palate ( p = .002) and complete cleft palate ( p = .01) were significantly more affected by tooth agenesis than other cleft types. Agenesis of the premolars ( p = .043) and maxillary lateral incisors ( p = .03) were significantly more frequent in patients with unilateral complete cleft lip and palate.

Conclusions

The present study revealed a high frequency of dental anomalies in nonsyndromic cleft lip and/or palate patients and further demonstrated that patients with unilateral cleft lip and palate were frequently more affected by dental anomalies than those with bilateral cleft lip and palate. Moreover, our results demonstrate that dental anomalies should be considered during dental treatment planning for individuals affected by nonsyndromic cleft lip and/or palate.

Taurodontism in deciduous molars

Taurodont teeth are characterised by large pulp chambers at the expense of roots. An enlarged pulp chamber, apical displacement of the pulpal floor and no constriction at the level of the cement-enamel junction are the characteristic features of taurodont tooth. It appears more frequently as an isolated anomaly but its association with syndromes and other abnormalities have also been reported. Permanent dentition is more commonly affected than deciduous dentition. This paper presents a case report of taurodontism in relation to mandibular deciduous second molars.

Dental findings and oral health status in patients with mucopolysaccharidosis: a case series

OBJECTIVE

To present a mucopolysaccharidosis (MPS) case series evaluating oral manifestations (clinical and radiographic), oral health status and discussing its implications.

PATIENTS AND METHODS

All patients with MPS attending the Genetics clinic/Brazil were evaluated by means of anamnesis, clinical and radiographic examinations.

RESULTS

The final sample consisted of 12 subjects (nine males and three females), with ages ranging from 3-31 years old. Concerning oral health, it was observed high levels of caries and periodontal problems. About oral manifestations, this study clinically observed more cases of delayed tooth eruption, thickness of alveolar process and thick lips. Radiographically, it was observed alterations on condyle, mandibular ramus and joint fossa.

CONCLUSION

The dental changes in MPS population are high and consequently it is important to know them for differential diagnoses, early treatment intervention, prevention and education of both patients and parents/caregivers about oral health.

Supernumerary teeth vary depending on gender

The presence of supernumerary teeth (ST) is a dental developmental anomaly of patterning and morphogenesis. Its variability of morphology, location and developmental timing can shed light on its etiology. In this work we report ST patterns. Orthopantomograms of 1,166 pediatric subjects were examined and the morphology, location and timing of the formation of ST were determined. The frequency of supernumerary teeth in the studied population was 2.3% (n = 27). Twenty-five subjects presented one ST. Maxilla midline was the most commonly affected region (nine cases). We noted high incidence of conical morphology in the midline region. Only teeth with tuberculate morphology presented delayed formation. ST in the midline region occurred more often in males whereas ST in the incisor region were more common in females. In conclusion, ST patterns vary depending on gender.

Oligodontia: A Case Report and Review of Literature

Oligodontia, a form of hypodontia commonly seen in permanent than in deciduous dentition. It is defined as the congenital absence of six or more teeth, excluding third molars. It is relatively a rare condition that can occur either as an isolated finding or as part of a syndrome. A case of nonsyndromic oligodontia in a 12-year-old boy with congenital absence of all permanent teeth except the premolars (excluding third molars) and over-retained deciduous dentition with conical shaped anteriors is reported. The prevalence, possible etiological factors and treatment options of the condition is reviewed.

Side of Dental Anomalies and Taurodontism as Potential Clinical Markers for Cleft Subphenotypes

Objective

The aim of this work was to investigate in more detail the dental clinical features that could serve to define subphenotypes of oral clefts.

Design

Dental records of oral cleft subjects from a group of 164 cases were examined, and 157 were included in this study. In addition, 65 families with two or more siblings born with clefts and 30 control families were evaluated to determine whether dental phenotypes were sporadic. Type of oral cleft and dental phenotypes (tooth agenesis, supernumerary teeth, taurodontism, dental transposition, and microdontia) outside the cleft area were investigated. Association of dental anomalies with preferential subtypes of cleft (subphenotype) was assessed.

Results

A total of 74 subjects presented at least one developmental dental anomaly. Tooth agenesis was the most common dental anomaly (28.6%), followed by taurodontism (15.2%). Supernumerary teeth were associated with cleft palate only ( p = .05). The absence of maxillary left lateral incisors was significantly associated with unilateral right cleft lip ( p = .02). Bilateral clefts were strongly associated with bilateral dental anomalies ( p < 0.001). In the cleft lip and palate group, tooth agenesis was associated with dental transposition ( p = .03) and with supernumerary teeth ( p = .009). Subjects with oral clefts have a higher risk of tooth agenesis (odds ratio = 3.33; 95% confidence interval, 1.18 to 10.13) and taurodontism (odds ratio = 3.95; 95% confidence interval, 2.28 to 6.82). Tooth agenesis, microdontic upper lateral incisors, and supernumerary teeth were most commonly found in unaffected siblings and parents of children born with clefts in comparison with families with no family history of clefts ( p = .01).

Conclusion

The preferential associations between specific cleft types with dental phenotypes suggest dental anomalies can be used as clinical markers to define the subphenotype isolated cleft lip and palate.

MMP1 and MMP20 contribute to tooth agenesis in humans

OBJECTIVE

Variations in genes that are critical for tooth formation may contribute to the tooth agenesis. MMPs are potential candidate genes for dental alterations based on the roles they play during embryogenesis. The aim of this study was to investigate the possible association between MMP1, MMP3, and MMP20 and tooth agenesis.

METHODS

One hundred sixty-seven nuclear families from two different populations were analysed, 116 from Brazil and 51 from Turkey. Probands had at least one congenitally missing tooth. DNA samples were obtained from blood or saliva samples and genotyping was performed using TaqMan chemistry. In addition, Mmp20 was selected for quantitative real-time polymerase chain reaction analysis with SYBR Green I Dye in mouse tooth development.

RESULTS

Associations between tooth agenesis and MMP1 (p=0.007), and MMP20 (p=0.03) were found in Brazilian families. In the total dataset, MMP20 continued to be associated with tooth agenesis (p=0.01). Mmp20 was not expressed during the initial stages of tooth development.

CONCLUSION

Our findings provide evidence that MMP1 and MMP20 play a role in human tooth agenesis.

Klinefelter syndrome presenting as behavioral problems in a young adult

BACKGROUND

An 18-year-old Somali man presented to a primary care clinic to investigate a potential pathophysiological reason for behavioral problems at school that had arisen in the past 1-2 years. A previous physical examination at school revealed the patient to have small, firm testicles which prompted further testing.

INVESTIGATION

Thyroid function and levels of prolactin, total testosterone, follicle-stimulating hormone and luteinizing hormone were determined. Testes were measured. Chromosome analysis testing was performed to determine the patient's karyotype.

DIAGNOSIS

Klinefelter syndrome with a 47,XXY karyotype.

MANAGEMENT

Testosterone replacement therapy was recommended, but the patient declined treatment.

Dental agenesis: genetic and clinical perspectives

Dental agenesis is the most common developmental anomaly in humans and is frequently associated with several other oral abnormalities. Whereas the incidence of missing teeth may vary considerably depending on dentition, gender, and demographic or geographic profiles, distinct patterns of agenesis have been detected in the permanent dentition. These frequently involve the last teeth of a class to develop (I2, P2, M3) suggesting a possible link with evolutionary trends. Hypodontia can either occur as an isolated condition (non-syndromic hypodontia) involving one (80% of cases), a few (less than 10%) or many teeth (less than 1%), or can be associated with a systemic condition or syndrome (syndromic hypodontia), essentially reflecting the genetically and phenotypically heterogeneity of the condition. Based on our present knowledge of genes and transcription factors that are involved in tooth development, it is assumed that different phenotypic forms are caused by different genes involving different interacting molecular pathways, providing an explanation not only for the wide variety in agenesis patterns but also for associations of dental agenesis with other oral anomalies. At present, the list of genes involved in human non-syndromic hypodontia includes not only those encoding a signaling molecule (TGFA) and transcription factors (MSX1 and PAX9) that play critical roles during early craniofacial development, but also genes coding for a protein involved in canonical Wnt signaling (AXIN2), and a transmembrane receptor of fibroblast growth factors (FGFR1). Our objective was to review the current literature on the molecular mechanisms that are responsible for selective dental agenesis in humans and to present a detailed overview of syndromes with hypodontia and their causative genes. These new perspectives and future challenges in the field of identification of possible candidate genes involved in dental agenesis are discussed.

Studies of dental anomalies in a large group of school children

The identification of specific patterns of dental anomalies would allow testing the hypothesis that certain genetic and environmental factors contribute to distinct dental anomaly subphenotypes. A sexual dimorphism in tooth agenesis and its association with other dental anomalies has been suggested. The aim of this study was to investigate a large group of children to define dental anomaly subphenotypes that may aid future genetic studies. Orthopantamograms of 1198 subjects were examined and 1167 were used in this study. The frequency of tooth agenesis in the studied population was 4.8%. Male:female ratios varied from 2:1 in the agenesis of upper lateral incisors to 0.5:1 in premolar agenesis. The risk of infra-occlusion of primary molars and double formation of primary incisors was increased in individuals with tooth agenesis.